Assessment of implant position after total knee arthroplasty by dual-energy computed tomography.

BACKGROUND: Correct alignment of prosthetic components is the most important factor for the success of total knee arthroplasty (TKA). Dual-energy computed tomography (DECT) may be a reliable method in determining implant position after TKA. PURPOSE: To evaluate the accuracy and reproducibility of DECT in determining implant position after TKA. MATERIAL AND METHODS: Institutional review board approval was obtained. Forty-five patients (age 75.2 ± 6.4 years) prospectively underwent TKA at our institution between May and December 2012. DECT was performed 1 year after surgery, using an alignment similar to a standing position and generating images at an extrapolated energy of 120 kVp, in order to reduce metal artifacts. Implant position was evaluated by two independent readers. Intra- and inter-observer agreements were calculated. DECT measurements on implant position were compared with the preoperative planning based on radiographs. Additional clinical and DECT findings were taken into account. RESULTS: Metal artifact reduction was judged satisfactory in all cases. Regarding implant position assessed with DECT, good to excellent intra-observer (k: 0.74-0.87 and k: 0.75-0.88, respectively), and inter-observer agreement (k: 0.72-0.82) were found. In the comparison with preoperative planning, the widest limits of agreement were within 3.9° for the sagittal orientation of tibial component. A single patient with postoperative knee pain and stiffness had periprosthetic osteopenia, quadriceps femoris tendon calcifications, articular effusion, and excessive intrarotation of the femoral component. CONCLUSION: DECT is an accurate and reproducible tool for determining implant position after TKA.

Anatomy of anteromedial thigh perforators: CT-angiography study.

The anatomy of perforator for anteromedial thigh (AMT) flap is a very much-debated issue. In this article, we report AMT perforator vascular anatomy by CT-Angiography (CTA) evaluation of 68 consecutive healthy thighs. Perforators emergence, caliber, length, course, and source vessel in the central three fifth of the thigh were studied by a virtual coordinate system. A mean 4.94 ± 1.75 perforators per thigh (average length, 2.6 ± 0.99 cm) from superficial femoral artery (SFA) were found, emerging medial and lateral to sartorius muscle. A mean 0.4 ± 0.74 perforators per thigh (average length, 2.45 ± 0.97 cm) branched from rectus femoris artery, of which 80% were emerging lateral to sartorius muscle. A mean 0.62 ± 0.91 perforators per thigh (average length, 3.1 ± 1.23 cm) branched from an unnamed branch of SFA, of which 88% were emerging lateral to the sartorius muscle. Perforators' calibre was inferior to 1-5 mm in 177 perforators (51.6%), between 1.5 and 2 mm in 159 (46.7%), and over 2 mm in 7 (2%). The findings from this study show that AMT region is plenty of reliable perforators with overlapping fascial emergence but branching from three different source arteries.

Implant positioning in TKA: comparison between conventional and patient-specific instrumentation.

The number of total knee arthroplasty (TKA) procedures continuously increases, with good to excellent results. In the last few years, new surgical techniques have been developed to improve prosthesis positioning. In this context, patient-specific instrumentation is included. The goal of this study was to compare the perioperative parameters and the spatial positioning of prosthetic components in TKA procedures performed with patient-specific instrumentation vs traditional TKA. In this prospective comparative randomized study, 15 patients underwent TKA with 3-dimensional magnetic resonance imaging (MRI) preoperative planning (patient-specific instrumentation group) and 15 patients underwent traditional TKA (non-patient-specific instrumentation group). All patients underwent postoperative computed tomography (CT) examination. In the patient-specific instrumentation group, preoperative data planning regarding femoral and tibial bone resection was correlated with intraoperative measurements. Surgical time, length of hospitalization, and intraoperative and postoperative bleeding were compared between the 2 groups. Positioning of implants on postoperative CT was assessed for both groups. Data planned with 3-dimensional MRI regarding the depth of bone cuts showed good to excellent correlation with intraoperative measurements. The patient-specific instrumentation group showed better perioperative outcomes and good correlation between the spatial positioning of prosthetic components planned preoperatively and that seen on postoperative CT. Less variability was found in the patient-specific instrumentation group than in the non-patient-specific instrumentation group in spatial orientation of prosthetic components. Preoperative planning with 3-dimensional MRI in TKA has a better perioperative outcome compared with the traditional method. Use of patient-specific instrumentation can also improve the spatial positioning of both prosthetic components.

Role of the Apparent Diffusion Coefficient in the Prediction of Response to Neoadjuvant Chemotherapy in Patients With Locally Advanced Breast Cancer.

BACKGROUND: We evaluated the diagnostic performance of the baseline diffusion weighted imaging (DWI) and the apparent diffusion coefficient (ADC) in the prediction of a complete pathologic response (pCR) to neoadjuvant chemotherapy (NAC) in patients with breast cancer stratified according to the tumor phenotype. PATIENTS AND METHODS: We retrospectively studied 225 patients with stage II, III, and IV breast cancer who had undergone contrast-enhanced magnetic resonance imaging (MRI) and DWI before and after NAC, followed by breast surgery. RESULTS: The tumor phenotypes were luminal (n = 143; 63.6%), triple-negative (TN) (n = 37; 16.4%), human epidermal growth factor receptor 2 (HER2)-enriched (n = 17; 7.6%), and hybrid (hormone receptor-positive/HER2(+); n = 28; 12.4%). After NAC, a pCR was observed in 39 patients (17.3%). No statistically significant difference was observed in the mean ADC value between a pCR and no pCR in the general population (1.132 ± 0.191 × 10(-3) mm(2)/s vs. 1.092 ± 0.189 × 10(-3) mm(2)/s, respectively; P = .23). The optimal ADC cutoff value in the general population was 0.975 × 10(-3) mm(2)/s (receiver operating characteristic [ROC] area under the curve [AUC], 0.587 for the prediction of a pCR). After splitting the population into subgroups according to tumor phenotype, we observed a significant or nearly significant difference in the mean ADC value among the responders versus the nonresponders in the TN (P = .06) and HER2(+) subgroups (P = .05). No meaningful difference was seen in the luminal and hybrid subgroups (P = .59 and P = .53, respectively). In contrast, in the TN and HER2(+) subgroups (cutoff value, 0.995 × 10(-3) mm(2)/s and 0.971 × 10(-3) mm(2)/s, respectively), we observed adequate ROC AUCs (0.766 and 0.813, respectively). CONCLUSION: The pretreatment ADC value is not capable of predicting the pCR in the overall population of patients with locally advanced breast cancer. Nonetheless, an ameliorated diagnostic performance was observed in specific phenotype subgroups (ie, TN and HER2(+) tumors).